Respostas

2014-03-26T15:50:11-03:00
R=-9-(-7) = -2

a5=a1+(n-1)r
a5=-7 +(5-1)-2
a5=-7-8
a5=-15

S= (a1+a5).n/2
S=(-7-15).5/2
S=-22.5/2
S=-110/2
S= - 55
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